- 學位論文
適應性通道脈衝響應長度之估測及其實現於DVB-T之通道估測時 之效能
Adaptive Estimation of Channel Impulse Response and Its Performance Evaluation in DVB-T Systems.
摘要
台灣數位電視是採用歐規DVB-T系統，使用正交分頻多工(OFDM)傳輸技術，訊號傳輸途中除了雜訊干擾外，接收端會經由各種不同的路徑，接收到不同的相對延遲時間、振幅以及相位構成多重路徑效應，接收端與傳送端之間如果有相對的位移，接收信號會有頻率偏移的現象，相對的移動的速度越快都卜勒效應(Doppler Effect)會更加明顯，通道也會隨著時間而改變產生時變通道，不同的接收路徑會有不一樣的都卜勒偏移，而導致OFDM每個子載波間的正交性遭受到破壞產生載波間干擾，使得傳輸能力效能變差，因此本篇論文提出了適應性通道脈衝響應長度之估測方法，針對不同的通道環境適應性估測出通道脈衝響應長度，以輔助以FFT為基礎之通道估測技術，以提昇接收機之效能，本篇論文中，實作一維線性內插、二維線性內插以及轉換域處理等通道估測方法，探討運用在實際通道靜態接收和行動接收部分以及模擬通道TU6和long delay模型下效能的比較。
並列摘要
The system for digital TV is European DVB-T in Taiwan and it applies OFDM Transmission. Not only noise signals, the receiver also takes relative delay, amplitude and phase from different path during OFDM Transmission. Hence, it forms Multi-Path Effect. The receiving signal will have Frequency Offset Situation if there is relative displacement between receiver and transporter. If the movement gets faster, there will also be more Doppler Effect. As time goes by, DVB-T path could change to Time Varying Channel. There will be different Doppler Spread on different path and Doppler Spread could destroy Carrier’s orthogonality and lead to ICI effect. This study focus on Estimation for Adaptive Channel Impulse Response. It estimates Channel Impulse Response through different path and help on Estimation for FFT Basis and higher the efficiency of receiving machine. This study performs 1D Interpolation, 2D Interpolation and Transform Domain Process to find its application under real environment and simulated channels such as TU6 and Longdelay.